The rapid increase in the number of Chlamydial infections and the severe complications associated with this disease in humans has made it imperative to detect these agents in body fluids. The unique life cycle and characteristics of the Chlamydial agents in general present a significant health threat. In phase I of this research and development proposal, a qualitative method of detecting low numbers of Chlamydial trachomatis would be developed. This sensitive, rapid detector uses an enzyme immunoassay (EIA) system which will produce a colored spot on a filter paper in the presence of the agent. Antibodies specific for the Genus type antigens will be bound to small particles and to a readout enzyme. These antibodies will be mixed with the sample/specimen containing the agent, then filtered out onto a paper disk. A substrate solution will be applied and the enzyme will produce a color on the paper if the agent is present. This method is quick, sensitive and lightweight. The feasibility of this detector system is expected to be demonstrated in Phase I and an assay system sensitive specifically to 103 or fewer particles of pathogenic Chlamydial agents in less than 60 minutes assay time, is expected to be developed and optimized in Phase II.